Process for the preparation of an alkyl benzene

Abstract

The invention relates to a process for the preparation of an alkyl benzene by catalytic dehydrogenation of the corresponding alkenyl cyclohexene in the gas phase in the presence of a diluent. A characteristic feature is that at least a part of the alkyl cyclohexane in the reaction product is used as diluent. Hydrogen can be used as an additional diluent according to the invention.

We claim: 
     
       1. A process for the preparation of an alkyl benzene comprising dehydrogenating a feed containing the corresponding alkenyl cyclohexene in the gas phase using a catalyst and in the presence of a diluent to obtain a reaction product comprising said alkylbenzene and an alkyl cyclohexane, wherein said feed contains alkenyl cyclohexene and alkyl cyclohexane in a molar ratio between 10:1 and 1:10 wherein at least a part of the alkyl cyclohexane in the reaction product is used as diluent. 
     
     
       2. A process according to claim 1, wherein at least a part of the hydrogen present in the reaction product is used as diluent. 
     
     
       3. A process according to claim 1 or 2, wherein the alkyl cyclohexane is obtained by a distillation from the reaction product. 
     
     
       4. A process according to claim 2, wherein the alkenyl cyclohexene/hydrogen molar ratio in the feed to the catalytic dehydrogenation has a value between 2:1 and 1:100. 
     
     
       5. A process according to claim 1, 2 or 4, wherein 4-vinyl cyclohexene is dehydrogenated to ethyl benzene. 
     
     
       6. A process according to claim 1, 2 or 4, wherein the reaction is carried out in an adiabatically operated reactor.